Question

Two polarizing sheets have their transmission axes crossed so that no light gets through. A third sheet is inserted between the first two so that its transmission axis makes an angle θ with the transmission axis of the first sheet. Unpolarized light of intensity I0 is incident on the first sheet. Suppose that the middle sheet is replaced by two polarizing sheets. The angles between the transmission axes of the second, third and fourth sheets in the stack make angles of 30°, 60°, and 90°, respectively, with the transmission axis of the first sheet.

(a) What is the intensity of the transmitted light? (Use the following as necessary: I₀.)

I₄ =  

(b) How does this intensity compare with the intensity obtained using the original single middle sheet?choose the right answer...

1-The intensity with four sheets is the same as the intensity with three sheets.

2-The intensity with four sheets is less than the intensity with three sheets.  

3-The intensity with four sheets is greater than the intensity with three sheets.

Answer 1

Answer 2

The intensity of the transmitted light is when four sheets are present, 14-0 cos"Acos"A cos I. cos (30')cos (60-30)cos (90-30) รั cos 2 (30)cos 2 (30)cos 2 (30.) 0.211 COS The intensity of the transmitted light is when three sheets are present, cos cos Divide the equations 1,-Leos, θ, cos"A and 14-cosa cos* a cos"A I. cos cos2 82 cos COS cos e cos 3 The maximum value of cos e is 1 4 31 I. Therefore, the intensity with four sheets is less than the intensity with three sheets